System and method for preventing cross-contamination in flow generation systems

ABSTRACT

A system for preventing cross-contamination in single-limb ventilators is described. In one embodiment, the system includes an airflow generator connected in-line to a humidifier, a first check valve and a patient interface by a gas flow circuit. A controller is electrically coupled to the airflow generator, and a cartridge is connected to the gas flow circuit between a first point downstream of the humidifier and a second point upstream of the patient interface. The cartridge includes a bacteria filter and the first check valve. A method for preventing cross-contamination in single-limb ventilators and a method for providing gaseous flow through a single-limb ventilator are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional application No.62/288,058 filed on Jan. 28, 2016 incorporated herein by reference inits entirety.

BACKGROUND OF THE INVENTION

Flow generation systems can be generally described as systems thatgenerate a gaseous flow, for example airflow or a blend of ambient airand oxygen. A ventilator is one example of a flow generation system. Aventilator is a piece of medical equipment that delivers a flow of gas,such as a blend of oxygen and ambient air to the airway of a patient toassist in or substitute a patient's breathing. Most ventilators delivera blend of oxygen and air so that the patient receives a target oxygenconcentration greater than that of ambient air. Generally, ventilatorsutilize a combination of single-use or reusable disposable componentsfor the patient interface (e.g. a mask or mouthpiece connected toflexible tubing) and non-disposable capital equipment (e.g. air pumps,sensors, controller modules, humidifiers, etc.) that is used over aperiod of time among different patients. The patient interface can befor example a mouthpiece, mask (full face, nasal, pillow, total mask, orcombinations of these), endotracheal tube or tracheostomy tube.

Although there are a variety of ventilator designs currently used in thefield, most conventional designs will fall into either the single-limbor double-limb category. Single-limb ventilators typically come indifferent configurations. In certain types of single limbconfigurations, there is no “active” exhalation valve. Instead, a hole(or multiple holes) at or near the patient connection serves as a“passive” exhalation valve. However, in this configuration, since thehole(s) is not big enough to handle the entire exhalation flow, some ofthe exhaled flow travels back to the device. In an acute caresingle-limb circuit, a single tube is also used for inhalation andexhalation. Typically, a section of the tube near the patient'smouthpiece is equipped with an exhalation valve, which is switched onand off according to a pressure and/or flow signal measured by thesystem. The pressure and/or flow signal can detect when air is flowingfrom the ventilator equipment to the patient, causing the exhalationvalve to stay closed. The pressure and/or flow signal can also detectwhen air stops flowing, or when an upstream airflow is detected, causingthe exhalation valve to open. Double limb circuits are similar, exceptthat they have a second tube connecting back to the ventilator, wherethe exhalation valve is located in this case. The advantage of a singlelimb circuit is that it eliminates the issues of added bulk, weight andproduction costs that are present with double limb design. However, oneof the shortcomings of single-limb ventilators is cross-contamination ofthe ventilator, since exhaled gas from the patient can return to thededicated or non-disposable components of the ventilator system duringexhalation.

With reference now to prior art FIG. 1, a conventional single limbventilator circuit 10 is shown in the pneumatic schematic circuitdiagram. An air pump 12 is connected via an in-line gas flow circuit 20to a humidifier 16 and a patient interface 18. The patient interface 18can include the single-limb flexible patient tubing and a patientinterface for the patient to breathe through. A flow sensor 22 and apressure sensor 24 are positioned in the gas flow circuit 20, and theycommunicate measurements to a controller 14 that controls the air pump12. As demonstrated by the diagram, the equipment in this blower basedsingle-limb ventilator is exposed to contamination from the patient'sexhaled gas.

Currently, the only recommended method in preventing cross-contaminationis to add bacteria filters 42 at the ventilator outlet, as shown forexample in prior art FIG. 2A. If the medical facility or patient failsto use bacteria filters, the main body of the ventilator components areexposed to the patient exhaled gas, and subsequently susceptible tocontamination. In addition to the potential cross-contamination, for thecases of bacteria filter use, there are at least a couple of scenarioswhich could affect the proper ventilator functions. Many ventilatorsystems include integrated humidifiers, although some do not.Humidifiers (heated or non-heated) are usually required for patients whoare on ventilators. Typically, for ventilator systems that includeintegrated humidifiers, the bacteria filter is located downstream of thehumidifier (see for example FIG. 2A). However, one issue with locating abacteria filter downstream of the integrated humidifier is that watervapor in the gas often leads to improper function of ventilatorcomponents, negatively affecting proper ventilator function. In the caseof a ventilator system that is not equipped with an integratedhumidifier, such as systems that use an external humidifier 16′ (see forexample FIG. 2B), the bacterial filter 42′ can be located downstream orupstream of the external humidifier 16′. However, even for systems thatutilize an external humidifier 16′, where the bacteria filter 42′ can belocated between the ventilator outlet and the humidifier inlet, thechances of the bacteria filter 42′ being compromised due to thehumidified gas will remain high, again affecting proper operation of thecomponents of the ventilators. Some ventilators (or mainly sleep apneatherapy devices) are designed to be used without bacteria filtersaltogether (see for example FIG. 1). In this case, ventilators and theircomponents are naturally susceptible to contamination.

Thus, what is needed in the art is a ventilator system that can moreeffectively utilize a bacterial filter and a humidifier while minimizingthe risk of cross-contamination to dedicated ventilator components anddevices.

SUMMARY OF THE INVENTION

In one embodiment, a system for preventing cross-contamination in a flowgeneration apparatus includes an airflow generator connected in-line toa humidifier, a first check valve and a patient interface connection bya first gas flow circuit; a controller electrically coupled to theairflow generator; and a second check valve connected in-line to abacterial filter along a second gas flow circuit, the second gas flowcircuit connected to the first gas flow circuit between a first junctionupstream of the humidifier and a second junction downstream of the firstcheck valve; where a removable cartridge houses the bacterial filter andthe first check valve. In one embodiment, the removable cartridge housesthe second junction. In one embodiment, an exhalation valve iselectrically coupled to the controller and connected to the gas flowcircuit downstream of the airflow generator and upstream of thehumidifier. In one embodiment, a housing includes a cavity configuredfor accepting insertion of the cartridge. In one embodiment, theinsertion includes slidable, screw or quick connect insertion. In oneembodiment, the cavity is configured for allowing removal of thecartridge. In one embodiment, the removal includes slidable, screw orquick disconnect removal. In one embodiment, the housing at leastpartially defines at least one of the first and second gas flow circuit.In one embodiment, the housing includes a locking mechanism for securingthe cartridge within the cavity. In one embodiment, openings of thefirst and second gas flow circuit are configured to interface withopenings of the cartridge upon insertion. In one embodiment, the firstcheck valve is configured to restrict the upstream flow of gas. In oneembodiment, the second check valve is configured to restrict thedownstream flow of gas. In one embodiment, a flow sensor is electricallycoupled to the controller and connected to the gas flow circuitdownstream of the pump and upstream of the humidifier. In oneembodiment, a pressure sensor is electrically coupled to the controllerand connected to the first gas flow circuit downstream of the pump andupstream of the humidifier. In one embodiment, the airflow generator isone of a blower and a pressure generator. In one embodiment, theexhalation valve is one of a voice coil actuator, stepper motor valve,proportional solenoid valve and pneumatically piloted balloon valve. Inone embodiment, the cartridge includes an autoclavable medical gradematerial. In one embodiment, at least one of the first and second gasflow circuit includes a flexible plastic tubing. In one embodiment, atleast one of the first and second gas flow circuit includes rigid ormanifold tubing.

In one embodiment, a method for providing gaseous flow through a flowgeneration apparatus includes the steps of providing a downstreamgaseous flow to a first junction, where the first junction has a firstbranch including an inhalation circuit and a second branch including anexhalation circuit, where the inhalation circuit includes a humidifierin line with a first check valve, where the exhalation circuit includesa second check valve in-line with a bacterial filter, and where theinhalation circuit and the exhalation circuit extend to and mergedownstream of the first junction at a second junction; preventing gasfrom traveling through at least a portion of the exhalation circuitduring an inhalation phase; and preventing unfiltered gas from travelingthrough at least a portion of the exhalation circuit during anexhalation phase. In one embodiment, a portion of the exhalation circuitincluding the bacteria filter and the inhalation circuit including thefirst check valve is housed in a removable cartridge. In one embodiment,the second junction is housed in the removable cartridge. In oneembodiment, the second junction is connected to a patient interfaceconnection. In one embodiment, the method includes the step ofexhausting an upstream gaseous flow of air at a point upstream of thefirst junction during the exhalation phase. In one embodiment, at leastone of the first and second check valves is a pressure actuated checkvalve. In one embodiment, the exhalation phase is detected by one of aflow sensor and a pressure sensor upstream of the first junction. In oneembodiment, the gaseous flow includes a blend of oxygen and ambient air.

In one embodiment, a method for preventing cross-contamination in a flowgeneration apparatus includes removing a used cartridge from a cavity ina flow generation apparatus, the cartridge including a bacterial filterand a first check valve, the system including an airflow generatorconnected in-line to a humidifier, the first check valve and a patientinterface connection by a first gas flow circuit, a second gas flowcircuit connected to the first gas flow circuit between a first junctionupstream of the humidifier and a second junction downstream of the firstcheck valve, and a housing including the cavity, the housing configuredso that the first check valve is connected in-line with the first gasflow circuit when the cartridge is fully inserted into the cavity, andthe bacterial filter is connected in-line with a second gas flow circuitwhen the cartridge is fully inserted into the cavity; and inserting aprepared cartridge into the cavity. In one embodiment, the methodincludes the step of autoclaving a used cartridge to the preparedcartridge before the step of inserting. In one embodiment, the methodincludes disposing the used cartridge and providing a preparedcartridge. In one embodiment, the method includes the step of performinga first treatment on a first patient prior to the step of removing theused cartridge, where the first treatment utilizes the system forassisting the first patient's breathing. In one embodiment, the methodincludes the step of performing a second treatment on a second patientafter the step of autoclaving the cartridge, where the second treatmentutilizes the system for assisting the second patient's breathing. In oneembodiment, the method includes the step of measuring at least one of aflow and a pressure within the gas flow circuit downstream of theairflow generator and upstream of the humidifier; and opening anexhalation valve based on the measuring. In one embodiment, the methodincludes the step of restricting upstream movement of gas at a pointbetween the patient interface connection and the humidifier. In oneembodiment, the method includes the step of restricting downstreammovement of gas at a point between the bacterial filter and the patientinterface connection. In one embodiment, the method includes the step ofslidably removing the used cartridge. In one embodiment, the methodincludes the step of slidably inserting the autoclaved cartridge. In oneembodiment, the method includes the step of locking the cartridge withinthe cavity. In one embodiment, the method includes the step ofinterfacing openings of the gas flow circuit with openings of thecartridge upon insertion.

In one embodiment, a system for preventing cross-contamination in a flowgeneration apparatus includes an airflow generator connected in-line toa humidifier, a first check valve and a patient interface connection bya gas flow circuit; a controller electrically coupled to the airflowgenerator; and a cartridge receiving cavity connected to the gas flowcircuit between a first point downstream of the humidifier and a secondpoint upstream of the humidifier. In one embodiment, an exhalation valveis electrically coupled to the controller and connected to the gas flowcircuit downstream of the airflow generator and upstream of thehumidifier. In one embodiment, the cartridge receiving cavity isconfigured for slidable, screw or quick connect insertion of acartridge. In one embodiment, the cartridge receiving cavity isconfigured for allowing removal of a cartridge. In one embodiment, thehousing at least partially defines the gas flow circuit. In oneembodiment, housing includes a locking mechanism for securing acartridge within the cavity. In one embodiment, openings of the gas flowcircuit are configured to interface with openings of a cartridge uponinsertion. In one embodiment, the first check valve is configured torestrict the upstream flow of gas. In one embodiment, a second checkvalve is configured to restrict the downstream flow of gas. In oneembodiment, a flow sensor is electrically coupled to the controller andconnected to the gas flow circuit downstream of the pump and upstream ofthe humidifier. In one embodiment, a pressure sensor is electricallycoupled to the controller and connected to the gas flow circuitdownstream of the pump and upstream of the humidifier. In oneembodiment, the airflow generator is one of a blower and a pressuregenerator. In one embodiment, the exhalation valve is one of a voicecoil actuator, stepper motor valve, proportional solenoid valve andpneumatically piloted balloon valve. In one embodiment, the gas flowcircuit includes a flexible plastic tubing. In one embodiment, the gasflow circuit includes rigid or manifold tubing.

In one embodiment, a cartridge for a flow generation apparatus includesan inhalation circuit including a first check valve; and an exhalationcircuit including a bacterial filter; where the inhalation circuit andthe exhalation circuit merge at a junction downstream of the first checkvalve and the bacterial filter. In one embodiment, the inhalationcircuit is connected to a first opening in a housing of the cartridge.In one embodiment, the exhalation circuit is connected to a secondopening in a housing of the cartridge. In one embodiment, the junctionis connected to a third opening in a housing of the cartridge.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing purposes and features, as well as other purposes andfeatures, will become apparent with reference to the description andaccompanying figures below, which are included to provide anunderstanding of the invention and constitute a part of thespecification, in which like numerals represent like elements, and inwhich:

FIG. 1 is a pneumatic schematic circuit of a prior art ventilatorsystem.

FIG. 2A is a pneumatic schematic circuit of a prior art ventilatorsystem having an integrated humidifier, and FIG. 2B is a pneumaticschematic circuit of a prior art ventilator system having an externalhumidifier.

FIG. 3 is a pneumatic schematic circuit of a ventilator system accordingto one embodiment.

FIG. 4A is a pneumatic schematic circuit of a ventilator system with a3-way valve directing exhaled flow to a junction according to oneembodiment, and FIG. 4B is a pneumatic schematic circuit of a ventilatorsystem with a 3-way valve directing exhaled flow to a room air portaccording to one embodiment.

FIG. 5 is an exploded view of a ventilator system according to oneembodiment.

FIG. 6A is a perspective view of assembled components of a ventilatorsystem and the cartridge loaded according to one embodiment, and FIG. 6Bis a perspective view of assembled components of FIG. 6A, with certaincomponents being transparent.

FIG. 7 is an alternate exploded view of a ventilator system according toone embodiment.

FIG. 8 is a flow chart of a method for providing airflow through asingle-limb ventilator system according to one embodiment.

FIG. 9 is a flow chart of a method for preventing cross-contamination insingle-limb ventilator systems according to one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a more clear comprehension of the present invention, whileeliminating, for the purpose of clarity, many other elements found insystems and methods of preventing cross-contamination in single-limbventilators. Those of ordinary skill in the art may recognize that otherelements and/or steps are desirable and/or required in implementing thepresent invention. However, because such elements and steps are wellknown in the art, and because they do not facilitate a betterunderstanding of the present invention, a discussion of such elementsand steps is not provided herein. The disclosure herein is directed toall such variations and modifications to such elements and methods knownto those skilled in the art.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are described.

As used herein, each of the following terms has the meaning associatedwith it in this section.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “an element” means one element or more thanone element.

“About” as used herein when referring to a measurable value such as anamount, a temporal duration, and the like, is meant to encompassvariations of ±20%, ±10%, ±5%, ±1%, and ±0.1% from the specified value,as such variations are appropriate.

Ranges: throughout this disclosure, various aspects of the invention canbe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Where appropriate, the description of a range should beconsidered to have specifically disclosed all the possible subranges aswell as individual numerical values within that range. For example,description of a range such as from 1 to 6 should be considered to havespecifically disclosed subranges such as from 1 to 3, from 1 to 4, from1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well asindividual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5,5.3, and 6. This applies regardless of the breadth of the range.

Referring now in detail to the drawings, in which like referencenumerals indicate like parts or elements throughout the several views,in various embodiments, presented herein is are systems and methods forpreventing cross-contamination in single-limb ventilators.

As shown in the system pneumatic schematic circuit of FIG. 3, the system100 according to one embodiment includes an airflow generator 112connected in-line to a humidifier 116, a first check valve 117 and apatient interface 118. These components are connected by a first gasflow circuit 120, which in certain embodiments, can be formed byopenings or rigid tubular structures defined by the system housing(s),connections by flexible tubing, or a combination of both. In oneembodiment, the gas flow circuit includes rigid or manifold tubing. Incertain embodiments, the humidifier is replaced by an empty chamber or avoid. The airflow generator 112 can be of types known in the art, suchas blowers, fans, or pressure generators. In certain embodiments, thecheck valve is a resilient one-way valve, such as a duckbill valve. Thecheck valve can also be a 2-way valve this is electronically controlledby the controller 114 or a pneumatically piloted 2-way valve. The firstcheck valve 117 is configured to restrict the upstream flow of gas. Thesecond check valve 143 is configured to restrict the downstream flow ofgas. A controller 114 is wired to the pump, and it sends drive signalsto the pump during operation. The controller 114 can store program orhistorical data for controlling the breathing patterns of the patient.The controller 114 can also relay calculate drive signals for the airpump and valves within the system, based on programmed software and/orfeedback from sensors in the system. A cartridge 140 houses part of thefirst gas flow circuit 120, the first check valve 117 and the bacterialfilter 142. The cartridge 140 also houses part of the second gas flowcircuit 123. A second gas flow circuit 123 connects a second check valvein-line with the bacterial filter. The cartridge 140 is installeddownstream of a first junction 126 located upstream of the humidifier116, and the cartridge 140 includes a second junction 128 locateddownstream of the humidifier 116, the cartridge further including thefirst check valve 117. The branch of the second gas flow circuit 123including the second check valve 143 and the bacterial filter 142,extending between the first junction 126 and the second junction 128 maybe referred to as the exhalation circuit in certain embodiments. Thebranch of the first gas flow circuit including the humidifier 116 andthe first check valve between the first junction 126 and the secondjunction 128 may be referred to as the inhalation circuit in certainembodiments.

Junctions 126 and 128 may be open junctions that allow the free flow ofgas throughout the connected gas lines at the junctions. In certainembodiments, one or both of the junctions 126, 128 are 3-way valves thatcan be controlled electronically via the controller 114, pneumaticallypiloted or actuated by a pressure gradient during inspiration andexhalation. For example, with reference to FIG. 4A, in one embodiment,the cartridge 240 houses a 3-way valve 250 that directs flow from thehumidifier 216, to the PI (or junction between the 3-way valve and thePI), or directs the exhaled flow to the first junction 226. In anotherembodiment, with reference now to FIG. 4B, instead of venting tojunction 226 (shown in FIG. 4A), the 3-way valve instead vents to a roomair port 226′. With reference back to FIG. 3, in certain embodiments, ifa 3-way valve is used at a junction 126, 128, the redundant first and/orsecond check valves 117, 143 can be removed. If the second junction 128uses a three way valve, it can optionally be housed within the cartridge140. The second check valve 143 can optionally be included within thecartridge 140. In one embodiment, a junction valve is located at thesecond junction 128. In certain embodiments, the junction valve isconfigured to limit or block gas access to a particular branch of thejunction when gas transfer to that branch is not desired. For example,in one embodiment, a junction valve located at the second junction 128has a first position during an inhalation phase, blocking the downstreamgas flow to the bacteria filter 142, and a second position during anexhalation phase, blocking downstream gas flow to the humidifier 116.Similarly, and in addition, a junction valve can be located at junction128 that has a first position during an inhalation phase, blockingupstream gas flow to the bacteria filter, and a second position duringexhalation, blocking upstream access to the humidifier. In this case,the junction valve can be housed within the cartridge. The junctionvalve can be a flexible pressure actuated check valve, or an actuatingvalve that communicates with the controller 114 for receiving controlsignals to open or close corresponding with inhalation and exhaustion.In certain embodiments, the patient interface 118 includes a connectionport 118′ and the flexible tubing, mask and/or mouthpiece that thepatient breathes directly into. In certain embodiments, the patientinterface includes masks (e.g. nasal, full, total, pillow, orcombinations of these), a mouth piece, an endotracheal tube or atracheostomy tube. According to certain embodiments, the patientinterface 118 may or may not have intentional leakage. Intentionalleakage at the patient interface in the figures is shown merely as anexample embodiment. The cartridge 140 is a removable cartridge thatincludes a bacteria filter 142 connected-in line to the second checkvalve 143. The cartridge 140 in certain embodiments is constructed ofmaterials such as medical grade plastics that are capable ofwithstanding high temperature sterilization, are autoclaveable, or aresimilar of withstanding some type of sterilization or autoclavingchamber. In certain embodiments, the cartridge 140 is constructed forsingle or limited use as a disposable component. As shown in the circuitof FIG. 3, the position of the cartridge 140 preventscross-contamination between patients via the bacterial filter bypreventing the return of unfiltered air that could be contaminated backto the main body of the ventilator components such as the airflowgenerator 112. In certain embodiments where a junction valve is used,patient exhaled gas is prevented from returning to the main body of theventilator (e.g. junction 126 and upstream), and can optionally bevented out to atmosphere. The position of the cartridge 140 also makesit simple to be replaced between patients.

In one embodiment, the system 100 includes an exhalation valve 130 wiredto the controller 114 and connected to the gas flow circuit 120downstream of the airflow generator 112 and upstream of the humidifier116. The exhalation valve 130 can in certain embodiments be one of avoice coil actuator, stepper motor valve, proportional solenoid valve ora pneumatically piloted balloon valve. The exhalation valve 130 receivesa signal from the controller 114 to open or shut, and can also receivean instruction for partially opening. In certain embodiments, theexhalation valve 130 is located at the first junction 126, between thefirst junction 126 and the second check valve 143, or between the secondcheck valve 143 and the bacterial filter 142. In certain embodiments,the first junction 126 is eliminated when the exhalation valve 130 islocated along the exhalation circuit 123. A second exhalation valve orleak port for passive exhalation can be located at the first junction126, between the first junction 126 and the second check valve 143, orbetween the second check valve 143 and the bacterial filter 142. Some orall of the bacterial filter 142, second check valve 143, exhalationvalve 130 and an exhalation leak port can be implemented as a singlecomponent. One or more flow sensors 122 and pressure sensors 124 can bepresent within the gas flow circuit 120. In one embodiment, a flowsensor 122 is wired to the controller 114 and connected to the gas flowcircuit 120 downstream of the pump 112 and upstream of the humidifier116. A flow sensor can be placed along the exhalation circuit 123 forembodiments where the exhalation valve 130 is placed along theexhalation circuit (e.g. after the exhalation valve 130 when theexhalation valve 130 is between the second check valve 143 and thebacterial filter 142). In one embodiment, a pressure sensor 124 is wiredto the controller 114 and connected to the gas flow circuit 120downstream of the pump 112 and upstream of the humidifier 116. The flowand pressure sensors can receive measurements that indicate and measureevents such as pump airflow, exhalation airflow, pump pressure,exhalation pressure, etc. The controller 114 can use these measurementsto control airflow and exhalation levels accordingly, based on thedesired treatment begin administered to the patient.

With reference now to the views of FIGS. 5-7, a system 100 according toone embodiment has a housing 150 that includes a cavity 152 configuredfor accepting insertion of the cartridge 140. In certain embodiments,the geometry of the cartridge 140 and the cavity are cubic, so thatslidable insertion, removal and seating of the cartridge within thecavity is easily accommodated. In certain embodiments, the geometry ofthe cartridge 140 is a screw or quick connect mechanism, or anothermechanism as known in the art. As will be appreciated by those havingordinary skill in the art, the geometry of the cartridge and the cavitycan be any geometry that will allow for insertion, removal and seatingof the cartridge within the cavity for proper alignment of gas lines. Alocking mechanism 160, such as a hinged cover can also be utilized tosecure the cartridge 140 within the cavity 152. Other securingmechanisms known in the art such as snap-fit securement can be utilized.In certain embodiments, the system is configured to ensure that thecartridge is properly inserted, so that the bacteria filter 142 isproperly in-line with the check valve 143. This can be accomplished, forexample, by a cartridge 140 and cavity 152 geometry that only allows forone-way insertion. Alternatively, a metal contact pair can include onemetal contact positioned on the cartridge 140, and a second metalcontact positioned within the cavity 152, so that they only touch whenthe cartridge 140 is properly inserted within the cavity 152. Pairedcontacts of other materials such as plastic can be used, as would beunderstood by those having ordinary skill in the art. In certainembodiments, the system will not start, or will signal an error, whenimproper cartridge insertion is detected.

Rigid component housings can at least partially define the gas flowcircuit 120 (as shown with particular reference to FIG. 5). As shouldalready be apparent, the housing structure can be a manifold-typestructure for assembly, or alternately can be molded or formed into asingle structure. The gas flow circuit can also include flexibleconduits, such as plastic tubing, for connecting components of the gascircuit. Openings of the gas flow circuit 120 are configured tointerface with openings 121 of the cartridge 140 upon insertion of thecartridge 140 into the cavity 152, so that gas can flow through thebacteria filter and check valve, which are housed within the cartridge140. Ports are available for connecting the system to air supplies andpatient tubing. According to one embodiment, a port 170 is provided onthe cartridge for connection (e.g. 118′) to patient interface tubing. Aknob 172 is included as part of an encoder for user interface settings.One or more protrusions can also be included for interface with asecurement mechanism, such as for securement to a medical cart.

In one embodiment, a cartridge for a flow generation system or apparatusincludes an inhalation circuit having a first check valve and anexhalation circuit having a bacterial filter. The inhalation circuit andthe exhalation circuit merge at a junction downstream of the first checkvalve and the bacterial filter. The cartridge can be packaged andpre-loaded within the flow generation system, packaged separately, orpackaged in bulk as single-use disposable cartridges. Cartridges can beautoclavable for multi-use between different patients, or as mentionedabove, can be single-use disposable cartridges. In one embodiment, theinhalation circuit is connected to a first opening in a housing of thecartridge. In one embodiment, the exhalation circuit is connected to asecond opening in a housing of the cartridge. In one embodiment, thejunction is connected to a third opening in a housing of the cartridge.

By isolating patient exhaled unfiltered air that is potentiallycontaminated from the main body of the ventilator, cross-contaminationbetween patients can be prevented, even in the case of not usingbacteria filters at the ventilator outlet. The bacterial filter and gascircuit configuration only allows filtered air to go back towardsdedicated components such as the air pump, and keeps unfiltered orpotentially contaminated air forward or downstream of these components.This cross-contamination prevention mechanism can be implemented in theform of a cartridge and it can take several different configurations. Inaddition to the cartridge, employing an exhalation valve downstream ofthe main components such as the airflow generator could enhance theventilator function particularly during exhalation by venting exhaledair to the room. However, it should be noted that thiscross-contamination prevention mechanism should work without theexhalation valve. Cartridges according to embodiments of the inventioncan be disposable or autoclavable.

In one embodiment, as shown in FIG. 8, a method 200 for providinggaseous flow through a single-limb ventilator is shown. A downstreamgaseous flow is provided to a first junction 202. The first junction hasa first branch including an inhalation circuit and a second branchincluding an exhalation circuit. The inhalation circuit includes ahumidifier in-line with a first check valve. The exhalation circuit hasa second check valve in-line with a bacterial filter. The inhalationcircuit and the exhalation circuit extend to and merge downstream of thefirst junction at the second junction. Gas is prevented from travelingthrough at least a portion of the exhalation circuit during aninhalation phase 204, and unfiltered and potentially contaminated gas isprevented from traveling upstream through at least a portion of theexhalation circuit during an exhalation phase 206. This is becauseunfiltered and potentially contaminated air is prevented from passingthrough the first check valve or the bacterial filter. Filtered anduncontaminated air can however pass through the bacterial filter. Anupstream gaseous flow of air is exhausted upstream of the first junctionduring an exhalation phase 208. In one embodiment, a portion of theexhalation circuit, the bacterial filter, a portion of the inhalationcircuit, and the first check valve are all housed in a removablecartridge. In one embodiment, the second junction is connected to apatient interface. Throughout the embodiments described herein, PI 118can be or include a mask. In certain embodiments, the mask 118 can be adisposable component and can have for example 6 feet or less, 2 meters,3 meters or more of disposable tubing that connects to the ventilator.The internal diameter can be for example 10 mm or less, 15 mm, 19 mm, 22mm or more. These disposable components can also be autoclaved andreused in certain embodiments. The mask and its tubing can be changedout every time between patients and/or treatments. In one embodiment, atleast one of the first and second check valves is a pressure actuatedcheck valve. In one embodiment, the exhalation phase is detected by oneof a flow sensor and a pressure sensor upstream of the first junction.In one embodiment, the gaseous flow includes a blend of oxygen andambient air.

In one embodiment, as shown in FIG. 9, a method 300 for preventingcross-contamination in single-limb ventilators is described. First, thesystem is used on a first patient 302, rendering the cartridge used ornon-sterile. Then the used cartridge is removed from a cavity in aventilator system 304. Similar to embodiments described above, thecartridge includes a bacterial filter, and the system includes anairflow generator connected in-line to a humidifier, a first check valveand a patient interface by a gas flow circuit. A housing has the cavityfor accepting insertion of the cartridge. When the cartridge is fullyinserted into the cavity, the cartridge is connected to the gas flowcircuit between a first point downstream of the humidifier and a secondpoint upstream of the humidifier. The removed used cartridge is thenreplaced with a prepared cartridge 306, which in certain embodiments canbe a new cartridge removed from original packaging, or a previously usedcartridge that has been cleaned, treated, sterilized or disinfected. Inone embodiment, the used cartridge is autoclaved in a machine such as anautoclaving chamber. Once it is autoclaved, the sterile cartridge isconsidered prepared and inserted back into the cavity of the ventilatorsystem. In one embodiment, the used cartridge is disposed of andreplaced with a prepared cartridge that is a new cartridge. With theprepared cartridge inserted into the system, the ventilator system isready for use by a second patient 308, and the risk ofcross-contamination is minimized. In one embodiment, at least one of aflow and a pressure is measured within the gas flow circuit downstreamof the airflow generator and upstream of the humidifier, and anexhalation valve is opened based on the measuring. In one embodiment,upstream movement of gas is restricted at a point between the patientinterface and the humidifier. In one embodiment, downstream movement ofgas is restricted at a point between the bacterial filter and thepatient interface. In one embodiment, the used cartridge is twisting,unlatching or slidably removable. In one embodiment, the autoclavedcartridge is twisting, latching or slidably insertable. The cartridgecan be secured by a screw, quick connect or other type of connectionknown in the art. In one embodiment, the cartridge is locked within thecavity. In one embodiment, openings of the gas flow circuit interfacewith openings of the cartridge upon insertion.

The disclosures of each and every patent, patent application, andpublication cited herein are hereby incorporated herein by reference intheir entirety. While this invention has been disclosed with referenceto specific embodiments, it is apparent that other embodiments andvariations of this invention may be devised by others skilled in the artwithout departing from the true spirit and scope of the invention.

What is claimed is:
 1. A system for preventing cross-contamination in aflow generation apparatus comprising: an airflow generator connectedin-line to a humidifier, a first check valve and a patient interfaceconnection by a first gas flow circuit; a controller electricallycoupled to the airflow generator; a second check valve connected in-lineto a bacterial filter along a second gas flow circuit, the second gasflow circuit connected to the first gas flow circuit between a firstjunction upstream of the humidifier and a second junction downstream ofthe first check valve; a removable cartridge containing the bacterialfilter and the first check valve; and a housing comprising a cavity, thehousing configured so that the first check valve is connected in-linewith the first gas flow circuit and the bacterial filter is connectedin-line with the second gas flow circuit when the cartridge is fullyinserted into the cavity.
 2. The system of claim 1, wherein theremovable cartridge houses the second junction.
 3. The system of claim 1further comprising: an exhalation valve electrically coupled to thecontroller and connected to the first gas flow circuit downstream of theairflow generator and upstream of the humidifier.
 4. The system of claim3, wherein the exhalation valve is one of a voice coil actuator, steppermotor valve, proportional solenoid valve and pneumatically pilotedballoon valve.
 5. The system of claim 1, wherein insertion of thecartridge within the cavity comprises one of a slidable, screw or quickconnect insertion.
 6. The system of claim 1, wherein removal of thecartridge from the cavity comprises slidable, screw or quick disconnectremoval.
 7. The system of claim 1, wherein the housing at leastpartially contains at least one of the first and second gas flowcircuit.
 8. The system of claim 1, wherein the housing comprises alocking mechanism for securing the cartridge within the cavity.
 9. Thesystem of claim 1, wherein openings of the first and second gas flowcircuits are configured to interface with openings of the cartridge uponinsertion.
 10. The system of claim 1, wherein the first check valve isconfigured to restrict an upstream flow of gas.
 11. The system of claim1, wherein the second check valve is configured to restrict a downstreamflow of gas.
 12. The system of claim 1 further comprising: a flow sensorelectrically coupled to the controller and connected to the first gasflow circuit downstream of the airflow generator and upstream of thehumidifier.
 13. The system of claim 1 further comprising: a pressuresensor electrically coupled to the controller and connected to the firstgas flow circuit downstream of the airflow generator and upstream of thehumidifier.
 14. The system of claim 1, wherein the airflow generator isone of a blower and a pressure generator.
 15. The system of claim 1,wherein the cartridge comprises an autoclavable medical grade material.16. The system of claim 1, wherein at least one of the first and secondgas flow circuits comprises a flexible plastic tubing.
 17. A method forproviding gaseous flow through a flow generation apparatus comprising:providing a downstream gaseous flow to a first junction, wherein thefirst junction has a first branch comprising an inhalation circuit and asecond branch comprising an exhalation circuit, wherein the inhalationcircuit comprises a humidifier in line with a first check valve, whereinthe exhalation circuit comprises a second check valve with a bacterialfilter, and wherein the inhalation circuit and the exhalation circuitextend to and merge downstream of the first junction at a secondjunction; preventing gas from traveling through at least a portion ofthe exhalation circuit during an inhalation phase; and preventingunfiltered gas from traveling through at least a portion of theexhalation circuit during an exhalation phase; wherein a portion of theexhalation circuit comprising the bacterial filter and the inhalationcircuit comprising the first check valve is housed in a removablecartridge so that when inserted into a cavity of the apparatus, thefirst check valve is connected in-line with the inhalation circuit andthe bacterial filter is connected in-line with the exhalation circuit.18. The method of claim 17, wherein the second junction is housed in theremovable cartridge.
 19. The method of claim 17, wherein the secondjunction is connected to a patient interface connection.
 20. The methodof claim 17 further comprising: exhausting an upstream gaseous flow ofair at a point upstream of the first junction during the exhalationphase.
 21. The method of claim 17, wherein at least one of the first andsecond check valves is a pressure actuated check valve.
 22. The methodof claim 17, wherein the exhalation phase is detected by one of a flowsensor and a pressure sensor upstream of the first junction.
 23. Themethod of claim 17, wherein the gaseous flow comprises a blend of pureoxygen and ambient air.
 24. A method for preventing cross-contaminationin a flow generation apparatus comprising: removing a used cartridgefrom a cavity in a flow generation apparatus, the used cartridgecomprising a bacterial filter and a first check valve, the apparatuscomprising: an airflow generator connected in-line to a humidifier, thefirst check valve and a patient interface connection by a first gas flowcircuit, a second gas flow circuit connected to the first gas flowcircuit between a first junction upstream of the humidifier and a secondjunction downstream of the first check valve, and a housing comprisingthe cavity, the housing configured so that the first check valve isconnected in-line with the first gas flow circuit when the usedcartridge is fully inserted into the cavity, and the bacterial filter isconnected in-line with a second gas flow circuit when the used cartridgeis fully inserted into the cavity; and inserting a prepared cartridgeinto the cavity.
 25. The method of claim 24 further comprising:autoclaving the used cartridge to produce the prepared cartridge beforethe step of inserting.
 26. The method of claim 24 further comprising:disposing of the used cartridge and providing the prepared cartridge.27. The method of claim 24 further comprising: performing a firsttreatment on a first patient prior to the step of removing the usedcartridge, wherein the first treatment utilizes the apparatus forassisting the first patient's breathing.
 28. The method of claim 24further comprising: performing a second treatment on a second patientafter the step of inserting the prepared cartridge into the cavity,wherein the second treatment utilizes the apparatus for assisting thesecond patient's breathing.
 29. The method of claim 24 furthercomprising: measuring at least one of a flow and a pressure within thefirst gas flow circuit downstream of the airflow generator and upstreamof the humidifier; and opening an exhalation valve based on themeasuring.
 30. The method of claim 24 further comprising: restrictingupstream movement of gas at a point between the patient interfaceconnection and the humidifier.
 31. The method of claim 24 furthercomprising: restricting downstream movement of gas at a point betweenthe bacterial filter and the patient interface connection.
 32. Themethod of claim 24 further comprising: twisting, unlatching or slidablyremoving the used cartridge.
 33. The method of claim 24 furthercomprising: twisting, latching or slidably inserting the preparedcartridge.
 34. The method of claim 24 further comprising: locking theprepared cartridge within the cavity.
 35. The method of claim 24 furthercomprising: interfacing openings of the first and second gas flowcircuits with openings of the prepared cartridge upon insertion.